FIG. 1 illustrates a portion of nuclear reactor used in a nuclear power plant. The reactor head (100) communicates with the reactor vessel (not shown) in which the nuclear reaction takes place. A head lift rig (106) is mounted over the reactor head (100) and contains the control element drive mechanism (CEDM) (105).
The CEDM (105) is used to extend control rods (not shown) into the fissionable material in the reactor core in which the sustained nuclear reaction is occurring. The number of control rods used and the extent to which the control rods are extended into the reaction area controls the rate at which the nuclear reaction progresses. In the event of an emergency, an additional set of control rods can be rapidly extended into the core to halt the nuclear reaction entirely.
To shield the CEDM (105) from the heat of the reactor vessel, a heat shield of insulation (101) is provided as shown in FIG. 1. However, this insulation (101) alone is insufficient to keep the optimal temperature in the head lift rig (106). Consequently, a cooling system is also provided to control the temperature in the head lift rig (106).
The cooling system includes, for example, a pair of pipes (107) through which cooled air is forced into the head lift rig (106). The cooled air flows through the head lift rig (106), around the CEDM (105) and into a chamber (103) between the insulation (101) and the main body of the head lift rig (106). Exhaust holes (102) are provided in this chamber (103) to allow the cooled air to complete its circulation.
While this cooling system is adequate to control the temperature in the head lift rig (106), obvious problems will arise if the cooling system malfunctions or must be turned off for any reason. Without the flow of air illustrated in FIG. 1, the temperature inside the head lift rig (106) will quickly rise if a nuclear reaction is ongoing, or will stay high even if no reaction is being sustained.
Consequently, there is a need in the art for a device and method of supplementing the cooling system for a CEDM in the head lift rig of a nuclear reactor.